Background

I have a module that uses TypedStruct to create structs. This is the code:

defmodule Shared.Data.Authorization do
  @moduledoc """
  Saves authorization details for a user. It also contains other details.
  """

  use TypedStruct

  alias Shared.Utils.Structs

  @type authorization :: %{
          (cookie :: String.t()) => String.t(),
          (token :: String.t()) => String.t()
        }

  @derive Jason.Encoder
  typedstruct enforce: true do
    @typedoc "Authorization information for a user"

    field(:cookie, String.t())
    field(:token, String.t())
  end

  @spec new(authorization()) :: __MODULE__.t()
  def new(%{"cookie" => cookie, "token" => token} = auth)
      when is_binary(cookie) and is_binary(token) do
    Structs.string_map_to_struct(auth, __MODULE__)
  end
end

The problem here is that Gradient does not seem to understand that t() is created, so it errors out:

 lib/data/authorization.ex: The function call on line 26 is expected to have type t() but it has type struct()
 24   def new(%{"cookie" => cookie, "token" => token} = auth)
 25       when is_binary(cookie) and is_binary(token) do
 26     Structs.string_map_to_struct(auth, __MODULE__)
 27   end

For additional context, here is the string_map_to_struct code:

  @spec string_map_to_struct(map, module | struct) :: struct
  def string_map_to_struct(data, target_struct) do
    data
    |> Morphix.atomorphiform!() # string_map to atom_map
    |> data_to_struct(target_struct)
  end

  @spec data_to_struct(Enumerable.t(), module | struct) :: struct
  def data_to_struct(data, target_struct), do: struct(target_struct, data)

Temporary fix

I decided to convert that code into its native form using defstruct:

defmodule Shared.Data.Authorization do
  @moduledoc """
  Saves authorization details for a user. It also contains other details.
  """

  alias Shared.Utils.Structs

  @enforce_keys [:cookie, :token]
  defstruct [:cookie, :token]

  @type authorization :: %{
          (cookie :: String.t()) => String.t(),
          (token :: String.t()) => String.t()
        }

  @typedoc "Authorization information for a user"
  @type t() :: %__MODULE__{
          cookie: String.t(),
          token: String.t()
        }

  @spec new(authorization()) :: t()
  def new(%{"cookie" => cookie, "token" => token} = auth)
      when is_binary(cookie) and is_binary(token) do
    Structs.string_map_to_struct(auth, __MODULE__)
  end
end

Gradient does not complain here.

Question

Is there a fix for this?
(other than removing typed struct?)